Police said the child lost his balance after his mother lifted him in a standing position onto the 4-foot-high wooden railing of an elevated, gazebolike structure that overlooks the enclosure. He toppled over the railing, hit a mesh shelf and landed on the ground of the open exhibit space, where he was set upon by the 11 dogs in the area.

The medical examiner’s office would not release the child’s name Sunday evening. Police said he and his 34-year-old mother are from Pleasant Hills and were visiting the zoo with cousins, an adult and another child.

Major Crimes Lt. Kevin Kraus declined to comment on potential charges and said the bureau will continue to investigate to determine if anything could have prevented the death.